1. Field of the Invention
The invention relates to a device that prevents long strands of vegetation and fibrous material, including grass, from wrapping around an exposed rotating shaft of a machine. In particular, the device is useful for preventing the shaft of a cutting head or bailing roll from being wrapped with fibrous material during use.
2. Background of the Invention
Cutters and other machines having rotating shafts, such as bailers, frequently experience wrapping problems wherein the grass, vegetation or other fibrous matter being worked on wraps around the rotating shaft. If a sufficient amount of wrapping occurs, it impedes rotation of the shaft, and causes an additional strain to be placed on the engine and shaft bearings. The wrapping problem is particularly prevalent when a rotating shaft is exposed to long vegetation, such as field brush, vines, grass and hay, for example.
Conventional lawn mowers having steel blades do not encounter a wrapping problem when the grass being cut is relatively short. Lawn mowers are able to cut the grass strands more than just once and expel the clippings from the housing with a strong blowing force created by the rotation of the blades. This cutting action, which produces short pieces of grass in combination with the blowing of the clippings out of the housing prevents most of the grass from wrapping around the shaft. When steel blade mowers are used to cut tall grass, however, a wrapping problem can be experienced. One method for coping with this problem is to provide a shaft having primary and secondary cutting elements. The primary cutting elements are typically steel blades such as those found on a conventional lawn mower and the secondary cutting elements are typically short steel blades positioned vertically above the primary blades for cutting any clippings that reach the shaft above the primary cutting blade. Once all of the vegetation is cut to a sufficiently short length, it cannot wrap around the shaft.
The wrapping problem in general, has been recognized, and several attempts have been made to avoid the problem. One such attempt is to prevent the rotating shaft of a machine part from being exposed to the material being cut, bailed or transported, etc. To accomplish this, a shroud or seal is provided between the rotating shaft and the bearing housing. This is intended to prevent the shaft from being exposed. Despite such attempts, however, the best function that a shroud can perform is to minimize the exposure of the area of the shaft that is in contact with the stationary bearing housing. Thus, even when a shroud is used to prevent wrapping, long strands of fibrous material are built up on the stationary part so that eventually other strands are able to become wrapped around the rotating shaft by working around the shroud.
Another problem with using shrouds results from a fibrous material pulverizing action that takes place between the rotating and stationary parts of the shroud arrangement. This occurs because even with the most elaborate shroud design, there is some exposure to the fibrous material being cut, bailed, transported, etc. As this fibrous material is pulverized, the pieces can work their way into the bearing housing and cause overheating of the bearings. Thus, although the shroud may be effective to prevent a conventional wrapping problem, the bearings are not protected from the secondary effects caused by the minimal amount of wrapping that still manages to take place. Accordingly, the bearings eventually need to be replaced in any event.
The wrapping problem addressed by the present invention exists with all types of machines that work in an environment where there is exposure to long strands of fibrous material, such as grasses, vines and brush. The problem is present with mowers, trimmers, bush hogs and even harvesters and bailers since each of these machines has a rotating shaft that comes into contact with long strands of fibrous material during their operation. The wrapping problem is not dependent on the orientation of the axis of the shaft. The shaft axis can extend vertically, horizontally or in any direction therebetween, and the wrapping problem still exists if the environment in which the machine is working is exposed to long strands of fibrous material.